Book/Report

FZJ-2018-03155

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Untersuchungen zur elektronischen Struktur der Hochtemperatursupraleiter mittels Photoelektronenspektroskopie

Dauth, B. H. (Corresponding author)FZJ*

1989
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/18690

Report No.: Juel-2308

Abstract: The electronic structure of various polycrystalline samples including the new YBaCuO- and BiCaSrCuO- high T$_{c}$, superconductors (HTSC) and related systems is investigated by photoelectron spectroscopy. Additional characterization is performed by conductivity measurements. In particular, the binding energy of the Cu - 2P$_{3/2}$ and the O - ls-levels of various HTSC is determined. The Cu - 2P$_{3/2}$ and the Cu - LVV auger spectra are used to estimate by two different methods the Coulomb correlation energy Ud,j, between Cu-3d electrons. The U$_{dd}$ value for all HTSC-samples lies between 6.0 and 6.5 eV; we conclude that the HTSC belong to the class of strongly correlated systems. There is no evidence for a pure Cu - 3d$^{8}$-ground state in the HTSC from the various spectroscopic methodsused. For the first time the controversial 531 eV oxygen line was shown to be an intrinsic electronic structure effect. Responsible for that feature holes in the oxygen p-band leading to O$^{-}$. This result is obtained by a special in situ oxygen treatment, which shows additionally that spectroscopy from polycrystalline HTSC samples leads to very similar results as spectroscopy from their single crystals counterparts. Sintered CuO-samples are obtained for the first time. The electronic structure of the sintered CuO turns out to be drastically different with respect to pressed CuO powder. For the first time a crossover resonance from a O - ls - into a Cu - 3d - level was observed with synchrotron radiation. This is additional evidence for the strong hybridization between the Cu - 3d and the O - 2p states. Photoemission spectroscopy shows that the holes in the HTSC's are located at the oxygen p-band. Fe and Al overlayers on the HTSC-samples induce a drastic change in the electronic properties of the interface: apparently oxygen is removed from the HTSC to the overlayer.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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